messages: pure builders for every event the bridge sends

src/messages builds Response, StateReport, DeferredResponse, ErrorResponse, ChangeReport and the scene, doorbell
and simple events from plain values; messageId and times are parameters, so a test compares whole objects.
StateBuilder collects properties checked by the descriptors, AlexaError and AlexaErrors carry the payload fields
of an error type. AlexaStatusMessage and AlexaErrorResponse move to src/compat and are written on the builders.
On the wire, against 1.5.2: a DeferredResponse has no context key, a ChangeReport has no correlationToken, the
namespace of an ErrorResponse follows its type, and a ChangeReport without a changed property is not published:
send() resolves "" and the bridge reports an error that names the endpoint.
143 tests pass (108 before).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

test/messages/state.test.js

@@ -0,0 +1,91 @@
+"use strict";
+// StateBuilder: the properties of one message, checked by the descriptors of the registry.
+const { test } = require("node:test");
+const assert = require("node:assert/strict");
+const {
+  BrightnessController, Capability, EndpointHealth, PowerController, RangeController, SchemaError, StateBuilder,
+  TemperatureSensor, messages,
+} = require("alex2node");
+
+const AT = "2026-09-28T10:00:00.000Z";
+const now = () => new Date(AT);
+
+test("set: the property of a described interface, its time from the clock of the builder", () => {
+  const state = new StateBuilder({ now }).set(PowerController, "powerState", "ON").set(BrightnessController, "brightness", 40);
+  assert.deepEqual(state.context, [
+    { namespace: "Alexa.PowerController", name: "powerState", value: "ON", timeOfSample: AT, uncertaintyInMilliseconds: 0 },
+    { namespace: "Alexa.BrightnessController", name: "brightness", value: 40, timeOfSample: AT, uncertaintyInMilliseconds: 0 },
+  ]);
+  assert.deepEqual(state.change, []);
+});
+
+test("set: a property has the time and the uncertainty it is given", () => {
+  const changedAt = "2026-09-28T09:12:00.000Z";
+  const [property] = new StateBuilder({ now })
+    .set(PowerController, "powerState", "OFF", { timeOfSample: changedAt, uncertaintyInMilliseconds: 6000 }).context;
+  assert.equal(property.timeOfSample, changedAt);
+  assert.equal(property.uncertaintyInMilliseconds, 6000);
+});
+
+test("set: a temperature is reported in the scale it is given in", () => {
+  const [property] = new StateBuilder({ now }).set(TemperatureSensor, "temperature", { value: 70, scale: "FAHRENHEIT" }).context;
+  assert.deepEqual(property.value, { value: 70, scale: "FAHRENHEIT" });
+});
+
+test("set: a value Alexa would not take is refused, the error names the interface and the property", () => {
+  const state = new StateBuilder({ now });
+  assert.throws(() => state.set(PowerController, "powerState", "on"), (err) => {
+    assert.ok(err instanceof SchemaError);
+    assert.match(err.message, /^Alexa\.PowerController: powerState: expected .*ON.*got "on"$/);
+    return true;
+  });
+  assert.throws(() => state.set(PowerController, "power", "ON"), /Alexa\.PowerController: power: not a property of the interface, which has powerState/);
+  assert.deepEqual(state.context, []);
+});
+
+test("set: a generic controller needs its instance, given with the property or by the capability", () => {
+  const state = new StateBuilder({ now });
+  assert.throws(() => state.set(RangeController, "rangeValue", 3), /Alexa\.RangeController: rangeValue: the interface has instances/);
+
+  const lift = new Capability(RangeController, { instance: "Blind.Lift", options: {} });
+  state.set(RangeController, "rangeValue", 3, { instance: "Blind.Tilt" }).set(lift, "rangeValue", 40);
+  assert.deepEqual(state.context, [
+    { namespace: "Alexa.RangeController", instance: "Blind.Tilt", name: "rangeValue", value: 3, timeOfSample: AT, uncertaintyInMilliseconds: 0 },
+    { namespace: "Alexa.RangeController", instance: "Blind.Lift", name: "rangeValue", value: 40, timeOfSample: AT, uncertaintyInMilliseconds: 0 },
+  ]);
+});
+
+test("setRaw: a property of an interface the library does not describe, nothing checked", () => {
+  const state = new StateBuilder({ now }).setRaw("Alexa.Vendor.Thing", "level", { anything: true }, { instance: "Thing.One" });
+  assert.deepEqual(state.context, [
+    { namespace: "Alexa.Vendor.Thing", instance: "Thing.One", name: "level", value: { anything: true }, timeOfSample: AT, uncertaintyInMilliseconds: 0 },
+  ]);
+});
+
+test("health: the connectivity of Alexa.EndpointHealth, with the reason when there is one", () => {
+  const state = new StateBuilder({ now }).health("OK").health("UNREACHABLE", "WIFI_AP_NOT_FOUND");
+  assert.deepEqual(state.context.map((property) => [property.namespace, property.name, property.value]), [
+    [EndpointHealth.namespace, "connectivity", { value: "OK" }],
+    [EndpointHealth.namespace, "connectivity", { value: "UNREACHABLE", reason: "WIFI_AP_NOT_FOUND" }],
+  ]);
+  assert.throws(() => new StateBuilder().health("ASLEEP"), SchemaError);
+});
+
+test("changed and unchanged: the list the properties that follow go to; add() names one", () => {
+  const state = new StateBuilder({ now, target: "change" })
+    .set(PowerController, "powerState", "ON")
+    .unchanged()
+    .set(BrightnessController, "brightness", 40)
+    .changed()
+    .health("OK")
+    .add(messages.property("Alexa.Vendor.Thing", "level", 1, { timeOfSample: AT }), "context");
+  assert.deepEqual(state.change.map((property) => property.name), ["powerState", "connectivity"]);
+  assert.deepEqual(state.context.map((property) => property.name), ["brightness", "level"]);
+});
+
+test("context and change are copies: the message built from them does not change with the builder", () => {
+  const state = new StateBuilder({ now }).set(PowerController, "powerState", "ON");
+  const report = messages.stateReport({ endpointId: "lamp-1", correlationToken: "ct", messageId: "m", context: state.context });
+  state.set(BrightnessController, "brightness", 40);
+  assert.equal(report.context.properties.length, 1);
+});